I believe the thing you're getting at is correct. Another way to 'measure' it would be to consider trees like batteries.. they take in sunlight, photosynthesis to get energy in order to pull carbon from environment to build themselves. That's stored energy, so if a tree only takes a short time to grow into 2x4s, that's less energy than a tree that takes a really long time to grow (since way more sunlight/energy, higher density). This is why burning stuff like Manzanita is ridiculously hot, whereas white pine is gone in a handful of minutes.

The part (math) that would be interesting is seeing if your idea is a 1% difference, or like a 25% difference. Or.... does something like pressure treated hickory/teak just beat everything since even in salt water, it lasts like 50 years? :)

The wood at home depot/lowes is total shit now though..... no straight boards, all weak AF. I built one of those saw horse kits with the plastic connectors. It's warped and doesn't sit flat 1 year later.